1. Field of the Invention
This invention relates to the process of drying photographic films and to an element produced thereby. This invention also relates to a process for drying gelatino silver halide films such that improved throughput is achieved. More specifically, this invention relates to gelatino silver halide elements produced by the aforesaid process and having improved physical characteristics such as a reduced propensity to develop kinks.
2. Background of the Invention
Kinks are defects that are sometimes produced in sensitized, gelatino, silver halide photographic elements. These defects are common in the field of X-ray films since these elements are coated at a considerably higher emulsion coating weight. The kinks usually occur where the film has been bent and may be of the sensitized or desensitized variety. There are some references made in the prior art to the addition of plasticizers or other adjuvant compounds to a photographic, gelatino, silver halide emulsion in order to reduce the propensity of the films coated therefrom to produce kinks. Some of these compounds are said to reduce the sensitized kinks and other the desensitized kinks. None have proven fully useful in modern, high speed medical X-ray films that are coated at high speeds using modern equipment. Here there are other problems such as the ability of the equipment to fully dry the film without causing fog problems. During the coating process it is common practice to chill and set the emulsion right after application to the support followed by raising the temperature to dry said emulsion. After this step, it is also common to condition the film so as to reduce so-called "drying fog". This conditioning step takes additional time and equipment sometimes up to 15 to 50% of the total dryer length. This then limits the capacity of the coating equipment. This limit in capacity is inefficient and is becoming intolerable in modern film making factories. There is a pressing need to develop a system that can solve the problems of kinking in a sensitized element and can also assist in speeding up the drying process during manufacture without producing drying fog and thus increase product through-put.
It is also known to add humectants and plasticizers to photographic emulsions for a variety of reasons. These reasons include the reduction of fog and kink improvement. When some of these prior art ingredients are added, problems can occur. For example, the emulsion can become too pliable and soft and this can result in formation of other surface defects.